Sunnah Following Importance from Quran Al-Hashr 59:7 Al-Ahzab 33:36,21,40, Al-Ma'idah 5:3

Allah says in Quran
Today I have perfected your religion for you and completed My blessing upon you, and I am pleased with Islam as a religion for you(Al-Ma'idah 5:3), 

Islam is the final divine religion. Prophet Muhammad (Sallallahu Alaihi Wasallam) is [the Messenger of Allah and the Seal of the Prophets(Al-Ahzab 33:40).

Importance of Kitab O sunnah.......
Annas reported that Rasulallah (Sallallahu Alaihi Wasallam) said: “I have left among you two things you will never go astray as long as you hold fast to them: the Book of Allah and my Sunnah. (Haakim)

TWO MERCY OF Allah on Mankind........... 
1. Holy Quran
2. Sunnah of the Prophet 

The Prophet (Sallallahu Alaihi Wasallam) is a blessed individual, whom Allah has sent as a role model for all people with his moral values:

[You have an excellent model in the Messenger of Allah for all who put their hope in Allah and the Last Day and remember Allah much(Al-Ahzab 33:21)

The Prophet (Sallallahu Alaihi Wasallam) is a role model for everyone with his faith, godliness, knowledge, and superior moral values. With his patience, trust in Allah, courage, devotion, closeness to Allah, justice, compassion, love, affection for believers, and foresight, he possessed moral values that are greatly admired by the faithful.

Importance of obeying the Prophet (Sallallahu Alaihi Wasallam) 
and adhering to his path in. One of these reads:

[Whoever obeys the Messenger has obeyed Allah. If anyone turns away, We did not send you [Muhammad] to them as their keeper.] (An-Nisaa' 4:80)

The Sunnah is the interpretation, explanation of, and commentary on the Qur'an. Therefore, no believer, neither man nor woman, has any right to reject it:

[When Allah and His Messenger have decided something, it is not for any man or woman of the believers to have a choice about it. Anyone who disobeys Allah and His Messenger is clearly misguided.] (Al-Ahzab 33:36)

[Whatever the Messenger gives you, you should accept, and whatever he forbids you, you should forgo. Have fear [and respect] of Allah — Allah is severe in retribution.] (Al-Hashr 59:7)
(Original source! Taken with thanks with some editing